Electrical resistance device or heater.



PATENTED APR. 21, 1903.

J. P. ROLLING.

ELECTRICAL RESISTANGB'DEVIGE OR HEATER.

APPLICATION FILED APR. 4' 1902.

N0 MODEL.

2 SHEETS-SHEET 1- PATENTED APR. 21, 1903.

J. F. BCLLING. ELECTRICAL RESISTANCE DEVICE 0R HEATER.

2 SHEETS-SHBET 2 APPLICATION FILED APR. 4. 1902. NO MODEL.

UNITED STATES PATENT OFFICE.

JOHANN FRIEDRICH ROLLING, OF FRANKFORT-BOOKENHEIM-ON-THE-MAIN,

GERMANY, ASSIGNOR, BY MESNE ASSIGNMENTS, TO PROMETHEUS ELEC- TRIO COMPANY, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

ELECTRICAL RESISTANCE DEVICE OR HEATER.

SPECIFICATION formingpart of Letters Patent N 0. 725,663, dated April 21, 1903.

Application filed April 4, 1902. Serial No. 101,332. (No model.)

To all whom it may concern:

Be it known that I, J OHANN FRIEDRICH BOLLING, engineer, a citizen of the German Empire, residing at Frankfort-Bockenheimon-the-Main, Germany, have invented a new and useful Improvement in Electrical Resistance Devicesor Heaters, of which the following is a specification.

My invention relates to an electrical resistance device or heater in the form of a strip which may easily be manufactured and which can be adapted to various objects and exchanged, if so desired.

The new resistance device or heater sub- I 5 stantially consists of a strip of mica having on its surface a layer forming the electrical resistance and a layer of suitable insulating material covering the resistance layer on the strip of mica and metal strips which with their ends are pressed against the resistance layer by the insulating-cover and which form the terminals of the electric circuit. A cover of sheet metal may be provided on one or both sides of the strip. The sheet-metal cover,

which rests on the insulating layer, is provided with cut openings which allow the metal strips forming the terminals of the electric current to hold out of contact with'the sheetmetal cover. The resistance layer may be 0 fixed on the strip of mica by applying a coating of a thin solution of metal to the mica and then heating the strip of mica to dry out the solvent in a well-known manner, which is described in the German Patent No. 85,262.

3 5 Resistance-strips of this kind are able to sustain high temperatures and are very durable when the mica is pressed against another surface. However, it is to be taken into consideration that strips of mica which are suitable 0 for the purpose of fixing a resistance layer on same generally aro not longer than two hundred millimeters.

The new electrical resistance device or heater is illustrated in the drawings.

Figure 1 shows the strip of mica with the resistance layer fixed on it in elevation and in section. Fig. 2 shows an insulating-cover for the resistance layer on the mica strip of Fig. 1 provided with the terminals of the elec- 5o tric current, likewise in elevation and in section. Figs. 3 and 4: show sheet-metal covers. Fig. 5 shows the finished heater. Figs. 6 and 7 show the finished heater in form of a collar. Figs. 8 to 10 show a modification where two strips of mica, each with a resistance layer fixed on it, are combined to one single resistance device.

In all figures the same parts are indicated by the same letters of reference.

a is the resistance layer.

27 isa strip of mica.

The resistance layer consists of a thin layer of metal or other conducting material fixed to the strip of mica. Said resistance layer is somewhat thicker in those parts where the terminals ofthe electric current are in contact with same than in the other parts, as in dicated in Fig. 1 of the drawings by the smaller intervals of, the dots representing the resistance layer.

0 is another strip of mica adapted to form a cover for the resistance layer at on strip b.

e represents strips of metal which are fixed to mica strip 0 by clips (I. and which form the terminals of the electric circuit. The metal strips e are brought in contact with one of their ends with the resistance layer a by putting the mica strip 0 in contact with that side of the mica strip 19 on whichv the resistance layer Ct is fixed. f is a strip of sheet metal adapted to be put on said mica strip a. The sheet-metal strip f has openings 2' cut in it, which form passages for the terminals d of the electric current. The small edges of said sheet-metal stripfare turned over and provided with holes 7t for screws Z in order to press the resistance. g is another strip of sheet metal adapted to be laid upon that surface of the mica strip 1) which is not provided with a resistance layer and to be combined 0 with said mica strips 17 c and with said sheetmetal strip f, preferablyby the sheet metal h, which is overturned on the length sides, as represented in Fig. 5. The finished heater may be bent in the form of a collar and the 5 ends of the strip connected by screws 1 in the holes 7c.

The operation of the new heater is as follows: The metal strips c are brought in contact with the terminals of an electric circuit,

and the heater in the form of a collar is put on a saucepan or some other object, which is to be heated and pressed against the walls of same by setting the screws Z. When the current is closed, the heating-collar becomes hot and transfers the produced heat to the pan, &c.

In the modification represented in Figs. 8 to 10 two strips of mica b, with resistance layers a, are connected one with another to form oneresistance-strip. The strips of mica b are shown as overlapping one another, Fig. 8. The sheet-metal stripfhas about double the length of the mica strips b and is provided with a third hole vlin its midst, besides the two holes 1' at its ends. Fig. 10 shows the several parts of the resistance device connected one with another in the same manner as formerly described with reference to Fig. 5. The ends of the strip may be connected in the same manner as indicated in Fig. 6 and the collar fixed to some object which is to be heated in the same manner as represented in Fig. 7. The terminals of the electric current may be brought into contact with the metal strips e on both ends of the strip, whereas the ends of the strips 6 in the midst of the heating-collar are connected with one another.

Instead of two strips with resistance layers any other number may be connected with one collar. Furthermore, the plate g may be dispensed with, and the several parts may be connected onewith another in any other suit able manner.

What I claim is 1. In an electrical resistance device or heater the combination with strips of mica having resistance layers fixed on them, of insulating-covers on said resistance layers, metallic terminals, each of them in contact with one of the resistance layers and a sheet-metal strip connected with said strips of mica and forming a support for same.

2. In an electrical resistance device or heater the combination with strips of mica having resistance layers fixed on them, of insulating-covers on said resistance layers, metallic terminals, each of them in contact with one of the resistance layers anda sheet-metal strip connected with said strips of mica and provided with holes forming passages for said metallic terminals.

3. In an electrical resistance device or heater the combination with strips of mica having resistance layers fixed on them,of insulating-covers on said resistance layers, metallic terminals, each of them in contact with one of the resistance layers and two sheetmetal strips holding the mica strips with resistance layers and their insulating-covers between them all said strips connected with one another.

4:. In an electrical resistance device or heater the combination with strips of mica having resistance layers fixed on them, of insulating-covers on said resistance layers, metallic terminals, each of them in contact with one of the resistance layers and sheet-metal supports for said mica strip and insulatingcover, the whole forming a collar adapted to firmly contact with the walls of objects which shall be heated.

5. In an electrical resistance device or heater the combination with strips of mica having resistance layers fixed on them, other strips of mica forming insulating-covers for said resistance layers, metallic terminals secured to one of the said strips and each of them in contact with one of the resistance layers, and sheet-metal supports for said mica strips the whole forming a collar.

6. An electric resistance device or heater element, comprising insulating-strips bent into curved form and provided with a conducting layer between the same, said strips being inclosed in a suitable casing provided with means for connecting the ends of said casing to each other, and electric terminals in the form of thin metallic strips extending through openings into contact with the con ducting layer, substantially as described.

7. An electric resistance device or heater element,comprising a metallic sheet provided with inturned edges, another metallic sheet adapted to fit within said inturned edges, insulating-strips with a conducting layer between the same arranged between said metallic sheets, and electric terminals extending through openings in the metal casing and into contact with the conducting layer for including the conducting layer in circuit, substantially as described.

8. An electric resistance device or heater, comprising two strips of flexible insulating material with a conducting layer between them, electric terminals in contact with said layer, a metal strip secured to said insulating-strips, and having openings in its ends, through which said terminals extend to effect contact with the layer,said strips being adapted to be bent into curved form, and fastening devices adapted to said openings to connect the ends of said metal strip, substantially as set forth.

9. In an electrical resistance device or heater, the combination of a strip of insulating material having a resistance layer thereon, an insulating cover-strip on said resistance layer, electric terminals connected to one of the insulating-strips and in contact with said resistance layers, and a metal support for said strips, said support formed with openings for the terminals and of greater area than said terminals, substantially as set forth.

10. In an electrical resistance device or heater, the combination of a strip of insulating material having a resistance layer thereon, an insulating cover-strip on said resistance layer, electric terminals connected to one of the insulating-strips and in contact with the conducting layer and extending externally of the casing, scribed.

12. An electric heating element or resistance device, comprising strips of refractory insulating material, an intermediate layer of conducting material of relatively high resistance, an inclosing casing and means connected therewith for tightly pressing'said strips together, and electric terminals in contact with the conducting layer, substantially as described.

substantially as de- 13. An electric heating element or resist ance device, comprising strips of refractory insulating material with an intermediate conducting layer, means for tightly pressing said strips together, and means for including said conducting layer in the supply-circuit, sub stantially as described.

14. An electric heating element or resistance device, comprising a strip of refractory insulating material, a layer of conducting material upon said strip, an insulating cov ering-strip, a metallic presser-plate upon the exterior thereof, a corresponding metallic plate upon the exterior of the first-mentioned insulating-strip, means for tightly pressing said metallic plates together upon the insulating-strips and conducting layer, and terminals in contact with the conducting layer and extending externally of the casing, substantially as described.

Signed this 22d day of March, 1902, at Frankfort-on-the-Main. v

JOHANN FRIEDRICH ROLLING. Witnesses:

JEAN GRUND, CARL GRUND. 

